condition mean min max ZT0-3 36.405975 28.1084 44.70355 ZT4-7 7.952695 7.952695 7.952695 ZT8-11 4.28027 4.28027 4.28027 ZT12-15 0 0 0 ZT16-19 15.3417 15.3417 15.3417 ZT20-23 18.99695 18.99695 18.99695